2. amps-preamps
  3. 1183509117

Bypassing capacitor caps , and caps in General

With regards to tube amps etc ...

Power Supply Filter Caps and Decoupling Caps:
Do you guys agree with the train of thought where high capcitance electrolytics are "slow" to respond to sudden quick music signals which demand a "quick" instantaneous supply of power to the tubes? I have read that bypassing with a smaller value film cap, either a 0.1 uF or a 1.0 uF + 0.01 uF can help "speed" things up. I have heard that this theory or practice is from the '80's (maybe they didn't have such good caps then) and that nowadays, it is preferrable to use good quality electrolytics (such as Black Gates) rather than just any old large cap.
Or does this apply to decoupling caps only? Decoupling caps are local power supply caps, yeah? How do these differ from large electrolytic filter caps, function wise? Don't they both do the same thing, to supply power to the tubes? Why the need of a local power supply? Seems like my TRL amp doesn't use decupling caps, but several large computer-grade electrolytics. These I believe are filter caps, rather than decoupling caps.

Signal Caps and Coupling Caps:
Similarly, bypassing is used in coupling caps too. I have read of pros and cons, and am not sure if it is worth trying. In short, I have been told that large value coupling caps have better bass, likewise with large speaker drivers. However, like the large speaker driver, it has poor high frequency. Similarly with large decoupling caps, they will have poor high frequency - hence the small bypass across it - essentially, adding a tweeter. Or you could add two bypasses to achieve a mid and a tweeter.

Black Gate Electrolytics:
Ok - these are mega expensive electrolytics and are known worldwide by enthusiasts as the best electrolytic out there. Audio Note Kondo makes very pricey gear - they don't use these for their electrolytics in the power supply. Why is that? I own a M7 phono stage and it uses what seems to me to be standard Nippon Chemi-Con caps - not Black Gates. How much improvement will Black Gates offer in comparison to the Nippon Chemi-Con caps if I was to replace these in the M7. Should I? I believe the Nippon Chemi-Con function as filter caps and are positioned around the mains input transformer.

V-Cap TFTF:
I have read too many astronomical improvements when other caps are replaces with these. I'm going to bring up Audio Note Kondo again. Has anyone replaced AN caps with these and got better results? Or even bypassing the AN caps with a V-cap. Should the V-cap be so excellent, it's a shame Kondo do not use them. Maybe they want to keep their gear 100% Japanese.

Comments and opinions appreciated.

Regards
David
linnmaster
gregm
3,409 posts
 
it is prefer(r)able to use good quality electrolytics (such as Black Gates)
That's correct, afa the statement goes -- I don't particularly like the BG however.

How much improvement will Black Gates offer in comparison to the Nippon Chemi-Con caps if I was to replace these in the M7. Should I?
My spontaneous answer would be, no, you shouldn't. Components specs and channel matching are much more important in a riaa than the brand name of a particular cap.
Unless you can match the replacement components to extremely tight tolerances, and have the exact value required by the particular circuit -- leave as is. (Or, ask the designer.)
linnmaster OP
45 posts
 
Hmm .... I guess "don't touch" is the general response.

Thanks heaps!

Regards
David
linnmaster OP
45 posts
 
Hey peoples,

What about bypassing of filter caps? Is that meant to affect the sound? Increasing filter capacitance (if allowable) adds considerable improvement in sound in my own experience as it holds the volatage more solid. I did this with a preamp. There was so much that was missing when the filter capacitance on the high tension line was much lower. Backgrounds are now black silent, and the music flows out with so much sense of space, its amazing. Bypassing (if I was to use it here on the high tension filter caps) would technically improve the stability of the voltage line, no? I think that angstrom research labs does this on their filter caps. It can be seen from their website.

-David

Regards
David
atmasphere's avatar
atmasphere
11,936 posts
 
Bypassing filter caps good, bypassing coupling caps bad.

Now some specifics: There are a lot of high frequency effects that can occur and you can't just bypass a power supply cap and get away with it, although sometimes you can. If you really want to do it right, it is a good idea to calculate or measure the lead impedances at various RF frequencies that are known to be troublesome (for example the ones that seem to show up on a high speed scope) so often the right bypass value *and where you put it* will not be intuitive!!

If you have trouble understanding the paragraph above, or understanding how to set up the right value from this, you are probably better off leaving things as they are, else you could wind up with a unit that has a 'mysterious hum' (oscillation) that was not there before...
More to discover